If you have an iPhone…you need to have the Instagram app! (seriously download it RIGHT now) It is my all time favorite app for simple photo editing. It lets you add a variety of vintage looks to your photos and it even lets you follow other people to see their pictures.
Below is a collage I made with some of the photos I have edited using the Instagram app. You may recognize some of these pictures if you follow me on twitter.
I made this collage using the website Mosaic Maker, which was very user friendly. You can choose between uploading photos or using the urls.